As is well known to those skilled in the art, it is desired to treat dilute solutions containing dissolved materials to obtain more concentrated solutions or alternatively to recover solvent (frequently water) which contains decreased concentrations of solute.
In certain locations, such as on ships or in arid geographical locations, the dilute solution of particular interest is sea water which typically contains about 3.5 w % dissolved solids usually referred to as salt. Use of this water for various purposes is severely circumscribed unless the salt content is decreased to below about 0.1 w %. For example, water containing a higher concentration of salt than this level should not be used for irrigation of crops; and potable water suitable for human consumption should contain not more than about 0.05 w % salt.
It has been found to be possible to utilize membrane systems to obtain water containing decreased content of salt. In this process, the charge liquid is brought into contact with a membrane film; and one component of the charge liquid preferentially permeates the membrane. The permeate is then recovered from the downstream side of the film.
Additional background may be obtained from (i) U.S. Pat. No. 4,411,787 to UOP as assignee of Riley; (ii) J. E. Cadotte et al J. Macromol. Sci-chem A15(J) P 727 (1981); (iii) L. T. Rozelle et al Chapter 12 in Reverse Osmosis and Synthetic Membranes. Sourirajan(Ed).
It is an object of this invention to provide a novel method for treating aqueous systems containing dissolved salts to yield an aqueous product containing decreased content of salts. Other objects will be apparent to those skilled in the art.